PURPOSE: To increase the color synchronization accuracy and the color reproduction performance of an index-type color picture tube by preparing the funnel of the said tube from a glass material which has a filter effect, and shows a good transmittance characteristic selectively to light discharged by an index phosphor.

CONSTITUTION: An electron beam 4 discharged from an electron gun 3 scans a three-original-color phosphor stripe 1 so as to make each phosphor with an original color to emit light in order. At the same time, the electron beam 4 discharges an optical indix siganl 5 when it passes across an index phosphor stripe 2. Then, the signal 5, after passing through a light receiving window 9, is received by a photoelectric converter 10, and is changed into an electro- index signal, which is used for switching and controlling (color synchronization) color signals applied to the image receiving tube. By preparing a funnel from a material which has a spectral transmission characteristic desirable for the luminous-spectrum distribution of generally used three original-color phosphors or index phosphors, the S/N ratio of an index signal detected with the photoelectric converter 10 is increased, and the color reproduction performance of the picture image is improved.